In British Pat. No. 748,727 there is described an inversion polymerization process which comprises forming an initial conversion of monomer to polymer of up to 20% by mass polymerization of the monomer in the presence of a suitable catalyst. In this portion of the polymerization, the monomer is the continuous phase. Thereafter, sufficient water is added to the polymerization system to cause a phase inversion wherein the water becomes the continuous phase forming a dispersion of the unpolymerized monomer in the water. This dispersion is then polymerized to convert essentially all of the remaining monomer to solid polymer. However, the disadvantage of such a process is that polymer buildup on the internal surfaces of the reactor or "poly" is excessive and requires radical means of cleaning said surfaces after each batch or run is made, such as a high pressure stream of water, solvent cleaning, various hydraulic and mechanical reactor cleaners, and the like, and none of these has proved to be the ultimate in polymer buildup removal. Further, after several runs are made, it has often been necessary to open the reactor and manually scrape the polymer buildup off the internal surfaces. An operation such as this is not only costly, both in labor and down-time of the reactor, but presents potential health hazards as well.
In U.S. Pat. No. 3,706,722 there is described an inversion polymerization process for producing polymers having improved uniformity in porosity, size and structure. This the patentees accomplished by incorporating a nonionic, monomer-soluble surface active agent in the initial continuous monomer phase. While producing a more porous polymer, the polymer buildup is still a problem and detracts from the use of said process on a commercial basis. This is particularly true when producing polymers and copolymers of vinyl chloride where the buildup problem and health hazard is more acute than with many other monomers.
Accordingly, there is a great need to produce polymers having uniform porosity, size and structure by the inversion polymerization procedure, which procedure would substantially eliminate polymer buildup.